Texas Instruments GC5325, User Manual, Page: 5 / 35

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Hardware Setup
Figure 2. Location of Local Oscillator Inputs
NOTE: If a different power level is used, make sure the LO power level at both transmit modulators
and the receive mixer are within the required specification. SMD coaxial connector switches
are provided throughout the RF section of the GC5325EVM. Two of them can be used to
measure the LO power at the transmit modulators, and one can be used to measure the
power of the LO going to the receive mixers. See the schematic for the exact reference
designator. The connectors normally pass the RF signal from pin 1 to pin 2 with minimal
loss. When a special test cable from Murata (part no. MXGS83RK3000) is inserted into these
switches, the signal path from pin 1 and pin 2 is disconnected, and the signal is then routed
from pin 1 to the test cable.
• The GC5325SEK is designed to operate over two different frequency ranges: 700 to 1400 MHz and
1600 to 3000 MHz. The user must make sure the LO source frequency is set to match the
configuration of the board. To support the two operating frequency ranges, the receive path contains
two separate RF mixers, along with a wideband amplifier and attenuator. The GC5325EVM default
configuration is with two active mixers installed. The EVM also has an option to be configured with
passive mixers if desired. Jumpers JP7 and JP8 determine which mixer is used in the feedback path,
while jumpers JP6 and JP9 provide power or not to the mixers.
Figure 3 , which is the actual silkscreen
that is labeled on the top right side of the GC5325 EVM, shows how to set these jumpers per the
desired mode of operation.
Figure 3. Mixer Jumper Definition
• Transmit (TX) outputs are located at SMA connectors J17 (TX0_OUT) and J18 (TX1_OUT). The
receive (RX) inputs (feedback) are located at SMA connectors J46 (RX0_IN) and J28 (RX1_IN). The
receive inputs must not exceed approximately -10 dBm. The user may need to provide an attenuator in
5 SLWU063F – April 2009 – Revised April 2011 GC5325 System Evaluation Kit
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